It may be useful, in a variety of settings, to utilize both a traditional engine (e.g., an internal combustion engine) and an infinitely variable power source (e.g., an electric or hydrostatic motor, a variable chain drive, and so on) to provide useful power. For example, a portion of engine power may be diverted to drive a first infinitely variable machine (e.g., a first electric machine acting as a generator), which may in turn drive a second infinitely variable machine (e.g., a second electric machine acting as a motor using electrical power from the first electrical machine). In certain configurations, power from both types of sources (i.e., an engine and an infinitely variable power source) may be combined for final power delivery (e.g., to a vehicle axle) via a continuously or infinitely variable transmission (“IVT”). This may be referred to as “split-mode” or “split-path mode” operation because power transmission may be split between the mechanical path from the engine and the infinitely variable path.
Split-mode operation may be attained in various known ways. For example, a planetary gear set may be utilized to sum rotational power from an engine and from an electric machine, with the summed power transmitted downstream within an associated powertrain. This may allow for delivery of power (e.g., to vehicle wheels) with an infinitely variable effective gear ratio.
Various issues may arise, however, including limitations relating to the maximum practical speed of the variable power sources, fuel efficiency, etc. Also, these IVTs may be relatively complex. They may include a large number of parts. As such, it may take a large amount of time to manufacture and assemble the IVT. Moreover, the IVT may be very bulky and may take up a significant amount of room within the vehicle. Likewise, the IVT may contribute significantly to the overall weight of the vehicle, which can negatively affect fuel efficiency.